Modification of PES-based nanofiltration membranes by addition of sodium citrate surfactant modified- iron oxide nanoparticles

The use of nanofiltration membranes has been attractive in many fields especially in water treatment due to high separation performance. The most used membranes are polymeric. However, the achievement of high mechanical stability and good separation performance is one of the important challenges for the application with various operating conditions. In this study, PES-based nanofiltration membranes were fabricated by the phase inversion method. The Fe3O4 nanoparticles with the concentration of 0.5 wt.% and different concentrations of sodium citrate were used in the membrane preparation. The FTIR analysis was used to investigate the formation of chemical bonding. Moreover, membrane morphology and surface topography were studied by FESEM and AFM analysis, respectively. The separation performance of membranes was examined by the contact angle, membrane porosity, water content, pure water flux (PWF), and salt rejection. The results showed the highest PWF (47 L/m2h) and salt rejection (68%) for M5 at 0.5 wt.% of iron oxide nanoparticles and 0.3 wt.% of sodium citrate. However, Na2SO4 rejection increased slightly compared with the pristine PES membrane (about 11%). But the PWF improved about 66% compared with the pristine PES membrane due to increase membrane hydrophilicity and better dispersion of Fe3O4 nanoparticles and the formation of more active sites for Na2SO4 adsorption. The good dispersion of nanomaterials led to reducing membrane roughness, and also the increase of hydrophilic groups led to improve antifouling properties of prepared membranes.